A technical challenge is faced by those of ordinary skill in the art of designing and manufacturing optical devices to provide compact and reliable optical sensing and monitoring devices including power monitors with application versatility that can be conveniently implemented in different optical systems to carry out the self monitoring and diagnostic functions. Specifically, as the optical network communication systems are more broadly employed to perform signal transmissions with higher bandwidths while various optical systems are becoming more complicate, the maintenance and trouble shooting of the optical systems become more difficult. For the purpose of reducing communication downtime and the costs required for system maintenance, diagnoses and repairs, there are ever increasing demands of “smart” systems provided with the self-monitoring, diagnostic and even self-correcting functions. A first step moving toward such systems is to introduce more sensing and monitoring devices in different optical system to carry out continuous sensing and detections of system and operation conditions. The sensor and monitors are implemented not only in the new systems but often are also required in the existing systems as well. Installation of sensors and monitors into existing systems often requires the use of smaller size sensors and monitors with broader range of operation versatility to fit into the existing configurations and operation conditions. Conventional techniques of optical sensing and monitoring devices are not able to provide the sensors and monitors with sufficient compactness, versatility and reliability, including the optical power monitors, suitable for such applications.
For these reasons, there is still a need in the art of design and manufacture of optical power monitors with smaller size, more operational versatilities and higher reliability to overcome the difficulties discussed above. Specifically, an improved and simplified configuration and method for making smaller and reliable optical power monitors with reduced production cost are required.